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Thorianite
Current inventory:  0 gems
 

Thorianite

  
Thorianite is named for its chemical composition containing thorium,
a highly radioactive element, which was named for Thor, the Scandinavian god of war.

Discovered in 1904;   IMA status: Valid (pre-IMA; Grandfathered)

 

Chemistry

 

 

Chemical Formula:

ThO2

 

Thorium Oxide

Molecular Weight:

264.04 gm

Composition:

Thorium

87.88 %

Th

100.00 %

ThO2

 

Oxygen

12.12 %

O

 

 

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/D.31-50

Nickel-Strunz 10th Ed. ID:

4.DL.05

 

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
L : With large (+- medium-sized) cations; fluorite-type structures

Related to:

Thorianite-Uraninite Series.

Varieties:

Aldanite, Uranothorianite

Synonyms:

α-Thorianite, β-Thorianite, γ-Thorianite, Uraninitte (of Coomaraswamy)

 

 

Crystal Data

   

   

Crystallography:

Isometric - Hexoctahedral

Crystal Habit:

Cubic crystals, rarely modified by {111} and {113}, to 9 cm, usually rounded to some degree (water worn)

Twinning:

Penetration twins on {111} very common

 

 

Physical Properties

   

 

Cleavage:

Poor on {001}

Fracture:

Irregular/Uneven to Sub-Conchoidal

Tenacity:

Brittle

Moh's Hardness:

6.5 - 7.0

Density:

9.70 - 9.80 (g/cm3)

Luminescence:

Radioactive

Radioactivity:

Very Strong; GRapi = 1,505,305.18 (Gamma Ray American Petroleum Institute Units)

Health Warning:

Contains thorium - always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest. Avoid prolonged exposure in proximity of the body. Store away from inhabited areas.

 

 

Optical Properties

   

   

Color:

Black, brownish black, dark gray, dark reddish brown, may have a bronzy tarnish; in transmitted light, dark brown, reddish brown, greenish; gray with red-brown internal reflections in reflected light.

Transparency:

Opaque; Transparent in very thin fragments

Luster:

Submetallic when fresh, altering to Resinous

Refractive Index:

2.20 - 2.35  Isotropic; may show anomalous anisotropism

Birefringence:

0.000;  Isotropic

Dispersion:

n/a

Pleochroism:

n/a

Anisotrophism:

May show anomalous anisotropism; red-brown internal reflections in reflected light.

 

 

Occurances

   

   

Geological Setting:

An accessory mineral in granite pegmatites, more rarely in carbonatites or serpentinites; commonly detrital in heavy mineral concentrates.

Common Associations:

Thorite, Zircon, Ilmenite, Cassiterite, Allanite (Sri Lanka); Phlogopite, Diopside, Spinel (Andolobe, Madagascar)

Common Impurities:

U, Ce, La, Pb, TR

Type Locality:

Balangoda, Ratnapura, Sabaragamuwa Province, Sri Lanka

Year Discovered:

1904

View mineral photos:

Thorianite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


Thorianite is a rare thorium oxide mineral that is strongly radioactive due to its throium content. It is more stongly radioactive than Thorite, another thorium mineral that contains both thorium and uranium. Thorium was originally discovered by Ananda Coomaraswamy in 1904 as Uraninite, but recognized as a new species by Wyndham R. Dustan. Thorianite is a rare mineral, but an even rarer as a faceted gem. Thorianite is usually black with a submetallic luster and Mohs hardness of 6.5 - 7.0.

Thorianite is mainly for collectors of rare and unusual gems, black gems or radioactive gems. Thorianite is a highly radioactive mineral and should be stored away from other minerals and gems that might be damaged by radioactivity. Human contact and exposure to Thorianite mineral specimens or gems should be limited!

Current sources are Balangoda, Ratnapura, Sabaragamuwa Province, Sri Lanka; Betroka, Madagascar, where very large crystals are found; and other locations including South Africa, Russia, USA and Canada.
 

  
Thorianite gems for sale:

Thorianite-001

Gem:

Thorianite

Stock #:

THORN-001

Weight:

1.9540 ct

Size:

5.53 x 4.98 x 3.39 mm

Shape:

Cut-corner rectangle

Color:

Black

Clarity:

Opaque

Origin:

Balagoda, Sri Lanka

Treatment:

None (natural)

Price:

SOLD (but we have others)

Pictures are of the actual gem offered for sale.
Gem images are magnified to show detail.

Thorianite-001

An extremely rare gem from Balangoda, Ratnapura, Sabaragamuwa Province, Sri Lanka.


 


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